Abstract
Most previous studies have focused on analgesic and anti-cancer activities for the conotoxins identified from piscivorous and molluscivorous cone snails, but little attention has been devoted to insecticidal activity of conotoxins from the dominant vermivorous species. As a representative vermivorous cone snail, the Chinese tubular cone snail (Conus betulinus) is the dominant Conus species inhabiting the South China Sea. We sequenced related venom transcriptomes from C. betulinus using both the next-generation sequencing and traditional Sanger sequencing technologies, and a comprehensive library of 215 conotoxin transcripts was constructed. In our current study, six conotoxins with potential insecticidal activity were screened out from our conotoxin library by homologous search with a reported positive control (alpha-conotoxin ImI from C. imperialis) as the query. Subsequently, these conotoxins were synthesized by chemical solid-phase and oxidative folding for further insecticidal activity validation, such as MTT assay, insect bioassay and homology modeling. The final results proved insecticidal activities of our achieved six conotoxins from the transcriptome-based dataset. Interestingly, two of them presented a lot of high insecticidal activity, which supports their usefulness for a trial as insecticides in field investigations. In summary, our present work provides a good example for high throughput development of biological insecticides on basis of the accumulated genomic resources.
Highlights
Cone snails, a large group of carnivorous predators, are usually classified into fish-hunting, snail-hunting and worm-hunting groups [1,2,3]
The main purpose of this work is to screen out conotoxins with high insecticidal activity, which can be used as synergistic genes for construction of recombinant baculoviruses or generation of transgenic crops (Figure 1)
Based on the reported peptide sequence of ImI, we screened the library of conotoxins from C. betulinus [15] by using the homologous alignment method
Summary
A large group of carnivorous predators, are usually classified into fish-hunting, snail-hunting and worm-hunting groups [1,2,3]. They are effectively venomous to worms, snails, and fishes by using a deadly combination of paralyzing conotoxins. The fish-hunting group contains the least number of species, while some of them are assessed as deadly to humans. A larger number of species belong to the snail-hunting group that is dangerous by means of their aggressive behavior, Toxins 2017, 9, 214; doi:10.3390/toxins9070214 www.mdpi.com/journal/toxins. The largest worm-hunting group contains about 80% of the Conus genus, while they seem to be nonthreatening [2,3,4].
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